I have a 44g planted hex with various tetras and a clown pleco. Yesterday I did a 50% pwc and re decorated the tank. I added a river rock I found. Before adding I scrubbed the you know what out of it and soaked it in boiling water a few times. When I woke up this am all my fish are at the top of tank gasping for air? Even the trumpet snails I've acquired with my plants, that usually stay buried and hidden, are making their way to the top? The obvious thing is my filter was accidentally turned off.,,ya I know!! I turned it on full power about 20 minutes ago however they have not stopped gasping. Haven't checked my levels yet. I have had zero problems with this tank. I have a Rena Filster xp3 (rated for up to 75g) so I know they have enough filtration. Should I be worried or does it take longer to get the O2 back up if the filter is left off? Any advice??